1. Field of the Invention
This invention relates to a method for treating patients with Alzheimer's disease to improve memory impairment and accompanying symptoms commonly associated with Alzheimer's disease and related disorders of memory.
2. Description of the Prior Art
One important strategy in Alzheimer's disease has been to attempt to compensate for the disturbance in cholinergic function by increasing brain acetylcholine levels. This has been achieved using physostigmine and tetrahydroaminoacridine which induce acetylcholinesterase inhibition. Use of physostigmine and tetrahydroaminoacridine has important deleterious limitations in that (1) physostigmine is a very short acting inhibitor; (2) tetrahydroaminoacridine may be hepatotoxic; (3) the clinical effect of physostigmine and tetrahydroaminoacridine are variable; (4) the biochemical effects of these drugs on the level of inhibition of brain acetylcholinesterase and on acetylcholine concentration at synapse are not known; (5) the relationship between these clinical and biochemical effects is not known; (6) adequate levels of inhibition in brain may not have been achieved in clinical trials to date; and (7) assaying cholinergic markers is methodologically difficult.
Many of the methodological problems mentioned here are inherent in the use of short acting inhibitors such as physostigmine which do not provide a sufficiently long period of steady state inhibition to allow the various factors to come to equilibrium.